Wintry Winter 25-26 Winter Battle Zone

[Webberweather53]

Getting an MJO event to orbit into the Western Hemisphere (phase 8-1) a majority of the time relies on the extratropical circulation carrying the signal along, because the SSTs aren't warm enough outside of the Indo-Pacific to couple directly with the ocean, except perhaps in big El Niño events.

Having a negative NAO makes these western hemisphere MJO orbits more likely to occur because the extratropical waves penetrate deeper into the tropics during -NAO:

You can basically think of this as a positive feedback, where the presence of a -NAO makes a phase 8-1 MJO more likely to occur, which also favors -NAO, etc.
https://journals.ametsoc.org/view/journals/clim/34/23/JCLI-D-21-0153.1.xml

 

[SnowNiner]

Need that look January … not December

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

 

[griteater]

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

We want to see that MJO continue on into 8-1 and out of the Maritime Continent to get the Pacific side rolling

 

[1300m]

I used to think that way, but last December gave me a quick inch of cold powder mood event. Gone by lunch but it was fun and cold.

Just to me a complete unknown how this winter shakes out. -EPO/+TNH worked great last year. Can we do it again? I have no idea but my eyes are on the pacific, pacific, pacific as it makes or breaks us every year it seems.

I still believe as much as ever that the -NAO is the most directly influential circulation on eastern U.S. winter weather, but I also agree that without Pacific cooperation we still struggle. It's just too hard to snow here with any destructive elements to the flow as we've seen time and time again.

 

[Webberweather53]

A few other things I think that are playing into our favor at least for December

Being in a La Niña with a slower-moving and more amplified MJO (due in part to the easterly QBO) makes a subsequent -NAO and weaker polar vortex/-NAM more likely.

Fig from Lee et al (2019)




The current global tropics SSTa are also almost the exact opposite of the MJO phase speed & SST correlation pattern derived from Suematsu & Miura (2021), favoring slower MJO events that typically have stronger and more consistent extratropical teleconnections as Yadav et al (2024) + Yadav & Straus (2017) and Tseng et al (2020) have argued respectively.

 

[griteater]

I think our best hope analog for Nov-Dec comes from year 2000.




Note the central North Pac low and NW Asia / E Europe high in the Nov image. That's a precursor to Strat PV weakening as shown here (from https://journals.ametsoc.org/view/journals/clim/23/12/2010jcli3010.1.xml)



From paper conclusions, "...The regional tropospheric anomalies that are best correlated with vortex weakening are found to be those that are in phase with (and thus amplify the magnitude of) the climatological extratropical planetary waves, strongly suggesting (though simplified modeling work is certainly necessary) that regional anomalies that amplify the climatological stationary waves will, on average, affect the vortex. The two regional anomalies that can most effectively modulate the vortex are the North Pacific low and the eastern European high. A low over the North Pacific tends to result in a dramatic increase in wave 1 leaving the troposphere and converging at the vortex, and a high over eastern Europe tends to result in a dramatic increase in wave 2 leaving the troposphere and converging at the vortex. A low over the northwestern Pacific (possibly associated with October Eurasian snow) has a similar, but weaker, effect than that of a low over the central Pacific."


Current Euro Weekly for Nov 5 - Dec 5...



Here's the Strat PV weakening that occurred in Nov-Dec 2000 at 10mb (upper strat) and 100mb (lower strat)


Was also going to post the image that Eric did about the MJO Phase 7 / Nina / NAO connection




Here was the MJO in Dec 2000 - it went into Phase 7 the 2nd week of Dec



Solar and QBO this year are good comparisons to 2000-2001 as well - max phase of the solar cycle and QBO is in the negative phase





Early and late winter strat warmings are favored in -QBO (East) / Solar Max winters

(From: https://journals.ametsoc.org/view/journals/atsc/61/23/jas-3297.1.xml)

 

[Webberweather53]

I have pretty high confidence December is gonna try to make things real interesting this year.

I can’t quite figure out what’s going to happen in the heart of the winter this year.

Do we get a mid winter thaw as we get an Indian Ocean to Maritime Continent orbit with another favorable S2S look later in January or do we keep the good times rolling throughout most of this period?

If the tropospheric circulation anomalies can get anchored into the stratosphere (a stratospheric warming event for ex), that’s probably how we can keep the good times rolling well into January.

The stratosphere likely won’t matter much for this first round of mjo forcing in December, but it probably will be an important factor in January and February

I.e. could help keep the -NAO/-AO going beyond the timescale of the initial mjo forcing (as mentioned previously) or enhancing wave reflection Feb (+TNH) if its strong by then.

 

[Webberweather53]

I think our best hope analog for Nov-Dec comes from year 2000.

View attachment 175824


Note the central North Pac low and NW Asia / E Europe high in the Nov image. That's a precursor to Strat PV weakening as shown here (from https://journals.ametsoc.org/view/journals/clim/23/12/2010jcli3010.1.xml)

View attachment 175827

From paper conclusions, "...The regional tropospheric anomalies that are best correlated with vortex weakening are found to be those that are in phase with (and thus amplify the magnitude of) the climatological extratropical planetary waves, strongly suggesting (though simplified modeling work is certainly necessary) that regional anomalies that amplify the climatological stationary waves will, on average, affect the vortex. The two regional anomalies that can most effectively modulate the vortex are the North Pacific low and the eastern European high. A low over the North Pacific tends to result in a dramatic increase in wave 1 leaving the troposphere and converging at the vortex, and a high over eastern Europe tends to result in a dramatic increase in wave 2 leaving the troposphere and converging at the vortex. A low over the northwestern Pacific (possibly associated with October Eurasian snow) has a similar, but weaker, effect than that of a low over the central Pacific."


Current Euro Weekly for Nov 5 - Dec 5...
View attachment 175828


Here's the Strat PV weakening that occurred in Nov-Dec 2000 at 10mb (upper strat) and 100mb (lower strat)
View attachment 175829

Was also going to post the image that Eric did about the MJO Phase 7 / Nina / NAO connection

View attachment 175830


Here was the MJO in Dec 2000 - it went into Phase 7 the 2nd week of Dec

View attachment 175831

Solar and QBO this year are good comparisons to 2000-2001 as well - max phase of the solar cycle and QBO is in the negative phase

View attachment 175832

View attachment 175833

Early and late winter strat warmings are favored in -QBO (East) / Solar Max winters

(From: https://journals.ametsoc.org/view/journals/atsc/61/23/jas-3297.1.xml)
View attachment 175834

What’s interesting about the latter linked study you showed is that during solar max/east QBO years (like this winter), the polar vortex does weaken in early winter but they note that this doesn’t often carry over into subsequent months (Jan-Feb).

What’s interesting is the polar vortex in solar max/east QBO winters starts out weaker in December then actually becomes significantly strong in January (less significantly positive in Feb), then weakens again in March.

Hmm

 

[griteater]

What’s interesting about the latter linked study you showed is that during solar max/east QBO years (like this winter), the polar vortex does weaken in early winter but they note that this doesn’t often carry over into subsequent months (Jan-Feb).

What’s interesting is the polar vortex in solar max/east QBO winters starts out weaker in December then actually becomes significantly strong in January (less significantly positive in Feb), then weakens again in March.

Hmm

Yeah, I think the hopeful goal would be to get things going in Dec and have that carry over into Jan via weakened SPV and slow moving MJO.

81-82 was also solar cycle max / -QBO (E) / cool enso and had an early warming